Sexual orientation is the direction of one's sexual interest towards members of the same, opposite, or both sexes. It is determined by a number of factors depending on a great variety of biological, cultural and social features; however, the latest research highlights the major role of different neurobiological mechanisms in males and females, which would make us address our preference towards the other sex, in order for us to have "normal" sexual intercourse to ensure reproduction. Among those factors, serotonin seems to play a crucial role: recent experiments on male mice showed the possibility of switching sexual orientation through an intervention on serotoninergic systems, and several works may offer evidence for this hypothesis to be proven. Most notably, differences in the expression of tryptophan hydroxylase enzyme isoforms between the sexes might influence the neurotransmission patterns which lead to the difference in sexual orientation.
Sexually dimorphic nucleus
Sexually dimorphic nucleus is a group of neurons which show gender differences in development between male and female individuals; those cells have thus been considered to be the key of the difference in sexual behaviour and preference.
These cells are located in the preoptic area of hypothalamus